A wide variety of different devices have been proposed for occluding body lumens and openings between body lumens in patients over the years. It is common for devices delivered intraluminally to be initially introduced in a low profile state, and upon reaching a target location adjusted to a deployed state. In the case of occlusion devices intended to limit or block flow of body fluid through a lumen, by necessity the device is delivered in a form not completely occluding the lumen, and then transitioned to a form where greater or total occlusion occurs or can commence. Various factors relating to this need to substantially change shape or size present challenges to successful design and exploitation of such devices.
Occlusion devices generally fall into two classes. Certain occlusion devices are self-expanding, relying upon internal spring biasing of the device to enable expanding once a restrictive force is relieved. Another class of occlusion devices rely upon a mechanism for driving expansion. Self-expanding devices of course offer the advantage of simplicity in delivery and deployment. Driven devices can be more complicated to deploy, but can have the advantage of greater control over deployment, and potentially improved prospects for relatively simple and straightforward recapture by reversing operation of an integral driven expander. Known devices and delivery systems have shown great promise, but there remains ample room for improvement.